For preventing fraud in the use of a taximeter, different systems have been designed. These systems use, for determining loaded driving, weight sensors, in the seats of the taxi and/or door switches adapted to determine the opening of the doors. An example of such a prior system, is described in WO 84/03161.
Such systems are not always foolproof, since, for example, transporting goods in the luggage space cannot be determined, and, moreover, the sensors or switches provided in the seats and/or doors can be easily made inoperative.
Fraud is, in the first place, only possible when the taximeter is in the free condition, since, in the occupied condition, the fare is indicated and is entered into a daily totalizing counter or memory. A safety system should, therefore, be adapted to operate at least in the free condition of the taxameter.
The door and seat switches of the above-mentioned prior system indicate when passengers have got on or off the taxi, which is recorded as a pulse on a recording disc, whereas switching on the taximeter will give rise to a continuous recording. Moreover the velocity and distance are recorded on the disc. From a comparison of the various traces recorded on a daily disc, tampering or too much unoccupied driving can be derived, but this is time-consuming. In this prior system, a protection against loaded driving without switching on the taximeter is present, in which case the fuel supply towards the engine is shut-off. However, this is undesirable since, then, the taxi may come to a standstill at a dangerous point. This shut-off can be cancelled by means of a key, e.g. in the case of driving at an agreed price, but this can, again, lead to improper use, and always requires a careful examination of the recording discs, which often cannot provide a very accurate indication of fraud.
These disadvantages of the prior system make it unsuitable for protecting a taxi company completely against fraud. It is an object of the invention to provide a system which can ensure such a protection.